To investigate the efficacy and safety of enteric-coated mycophenolate sodium (Myfortic) as compared to intravenous cyclophosphamide in the treatment of active nephritis. The primary outcomes are complete and partial renal remission, as assessed by renal function, urinary sediment and proteinuria in patients with International Society of Nephrology/ Renal Pathology Society (ISN/RPS) class III or IV lupus nephritis.